17A. Synthesis of 2-nitro-6-(trifluoromethyl)phenol
Concentrated nitric acid (1.5 mL) was added slowly and dropwise to a solution of commercially available 2-trifluoromethylphenol (2.5 g, 15.42 mmol) in acetic acid (3 mL) at 0 °C. The reaction mixture was stirred at room temperature for 10 min. After the dropwise addition was completed, the reaction mixture was continued to be stirred at 0°C for 5 minutes, then brought to room temperature and stirred for 10 minutes. Upon completion of the reaction, the mixture was poured into ice water and extracted with ether (3×). The ether extracts were combined, washed sequentially with water and saturated saline, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography with 0 to 10% ethyl acetate/hexane as eluent to afford the target product 2-nitro-6-(trifluoromethyl)phenol (1.4 g, 44% yield).
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